- Requirements for Suction by SMT Nozzles in Mounting: (1) No material throwing (the material throwing rate is within the allowable range). (2) No slippage (insufficient vacuum suction force may cause movement of electronic components in active positions after detection). (3) No sticking (electronic components are stably separated from the suction nozzle after qualified mounting).
- Basic Principle of Suction by SMT Nozzles: The principle of vacuum suction is to use the force generated by the pressure difference between the vacuum system and atmospheric pressure to grasp and move objects. This method of using pressure difference to stabilize or move objects is widely used in daily life, such as vacuum cleaners, vacuum suction hooks, and cupping therapy in traditional Chinese medicine. Vacuum applications are also very common in industrial production.
(1) Atmospheric Pressure and Atmospheric Pressure: According to the principles of fluid mechanics, all objects in the Earth’s atmosphere are subject to the force of gravity of the air, which is the atmospheric pressure. The atmospheric pressure acting on a unit area is the atmospheric pressure. The standard atmospheric pressure at sea level (1 atm) is approximately equal to the pressure exerted by a column of mercury 760 millimeters high (mmHg). Different fields, countries, and regions use different units of pressure. In this context, the commonly used unit of pressure is:
(2) Vacuum and Vacuum Degree: Generally, the term “vacuum” refers to a condition in which the gas pressure is lower than the atmospheric pressure, rather than a completely airless “vacuum.” In other words, the gas under vacuum conditions is less dense than the gas under atmospheric pressure. The degree of rarityfaction of the gas under vacuum conditions is measured by the “vacuum degree.” Conventionally, a high vacuum degree indicates that the gas pressure is much lower than atmospheric pressure, while a low vacuum degree indicates that the gas pressure is slightly lower than atmospheric pressure.
